Infections, no matter how mild, have adverse effects on nutritional status. The significance of these effects depends on the previous nutritional status of the individual, the nature and duration of ...the infection, and the diet during the recovery period. Conversely, almost any nutrient deficiency, if sufficiently severe, will impair resistance to infection. Iron deficiency and protein-energy malnutrition, both highly prevalent, have the greatest public health importance in this regard. Remarkable advances in immunology of recent decades have increased insights into the mechanisms responsible for the effects of infection. These include impaired antibody formation; loss of delayed cutaneous hypersensitivity; reduced immunoglobulin concentrations; decreased thymic and splenic lymphocytes; reduced complement formation, secretory immunoglobulin A, and interferon; and lower T cells and T cells subsets (helper, suppressor-cytotoxic, and natural killer cells) and interleukin 2 receptors. The effects observed with single or multiple nutrient deficiencies are due to some combination of these responses. In general, cell-mediated and nonspecific immunity are more sensitive than humoral immunity.
In the 1950s textbooks of nutrition made little or no mention of a relation to infection. The same was true for treatises on infectious disease. Relevant studies in experimental animals and a number ...of classical clinical observations were available pointing out the role of infection in precipitating nutritional disorders. However, clinicians and nutritionists did not recognize the importance of the relationship. The field and metabolic studies of the Institute of Nutrition of Central America and Panama (INCAP) in the 1950s demonstrated that malnutrition and infection in humans are generally synergistic. These studies stimulated the review of available evidence that resulted in the 1968 WHO monograph on “Interactions of Nutrition and Infection.” It provided extensive evidence for the role of infections in precipitating clinical malnutrition and for the impact of malnutrition on morbidity and mortality from infection. The high frequency of diarrhea in underprivileged young children led to intensive studies in many countries of its effect on nutritional status and to recognition of the high prevalence of “weanling diarrhea.” The effects of infection on nutritional status were then extensively and elegantly investigated at Fort Detrick, MD, and hormonal and cytokine mechanisms identified. The subsequent explosion in knowledge of cell-mediated immune mechanisms has led to an understanding of how malnutrition lowers this resistance. Today, recognition of the synergistic relationship between nutrition and infection influences most public health interventions to prevent malnutrition. J. Nutr. 133: 316S–321S, 2003.
Iron deficiency anemia affects a large number of women in developing countries, especially during child-bearing years. The hemoglobin concentration is useful for identifying iron deficiency anemia. ...The main objectives of this study were, first, to extend algorithms for calculating bioavailable iron from mixed diets, taking into account the enhancers and inhibitors of iron absorption under alternative assumptions on body iron stores. Second, a comprehensive longitudinal model was developed for the proximate determinants of hemoglobin concentration that included the subjects' dietary intakes, nutritional status, morbidity and socioeconomic factors and the unobserved between-subject differences. The model for hemoglobin concentration was estimated using three repeated observations on 514 free living women in Bangladesh. Socioeconomic factors affecting the iron intake from meat, fish and poultry and from all animal sources were also modeled. The main results were that bioavailable iron, women's height and mid upper arm circumference and intake of iron tablets were significant predictors of hemoglobin concentration. Increases in household incomes were associated with higher intake of iron from meat, fish and poultry and from all animal sources. The algorithms for estimating bioavailable iron showed the importance of assumptions regarding body iron stores and underscored the need to develop suitable algorithms for subjects in developing countries.
Lysine is a limiting amino acid in diets based on wheat as the staple. In experimental animals, prolonged dietary lysine inadequacy increases stress-induced anxiety. If observed in humans, such a ...result would have a strong implication for the relationship between nutrition and communal quality of life and mental health. As part of a 3-month randomized double-blind study, we tested whether lysine fortification of wheat reduces anxiety and stress response in family members in poor Syrian communities consuming wheat as a staple food. In the lysine-fortified group, the plasma cortisol response to the blood drawing as a cause of stress was reduced in females, as was sympathetic arousal in males as measured by skin conductance. Lysine fortification also significantly reduced chronic anxiety as measured by the trait anxiety inventory in males. These results suggest that some stress responses in economically weak populations consuming cereal-based diets can be improved with lysine fortification.
Three widely prevalent nutritional deficiencies are recognized to have the potential for permanent adverse effects on learning and behavior: protein-energy, iron, and iodine. Supplementation with ...adequate protein and calories during the first two years of life improves the cognitive performance of poorly nourished children, and the benefits may be even more robust years later when the children become adolescents and young adults. Iron deficiency is the most common global nutritional problem; among the earliest functions to be affected are those associated with the brain enzymes involved in cognition and behavior. The effects of iron deficiency during infancy appear to be irreversible. At older ages iron deficiency is intellectually and educationally disadvantageous independently of ethnicity and of physical and social environment. Even in areas where cases of cretinism due to iodine deficiency in the mother are few, the linear growth of the infant, its intellectual capacity, and certain other of its neurological functions are permanently compromised to varying degrees. In addition to these three most prevalent forms of deficiency, recent evidence suggests that cow's milk and infant formulas may lack sufficient omega-3 fatty acids for optimal development of the preterm infant and the neonate. Nutritional deficiencies are also potential contributors to impaired cognition in the elderly. Investments in education and community development would be more effective if the physical and cognitive capacity of underprivileged populations were not impaired by malnutrition.
A 1983 conference organized by United Nations University proposed an international network of food data systems (INFOODS) to address the need for and limitations of food-composition databases. ...Concerns of INFOODS include the acquisition and interchange of quality data on the nutrient composition of foods; the development of standards and guidelines for the collection, compilation, and reporting of food-component information; and support of a worldwide network of regional data centers for the generation, compilation, and dissemination of information on food composition. One goal of these centers is to assist in the development of appropriate national databases, especially in developing countries. Much has been accomplished by INFOODS, despite limited resources. Several important documents on food composition have been published, an international journal of food composition has been established, a directory of existing food-composition databases has been compiled, specific recommendations for the construction and use of food-composition databases have been developed, and a system of food nomenclature and coding has been created. Regional food-composition databases have been established throughout the world, with the goal of creating computerized systems that permit easy availability and interchange of food-composition data between regions and countries. In 1993 the Food and Agriculture Organization renewed its interest in the food-analysis capability of developing countries by becoming involved in INFOODS efforts.
1) Most humans, like other mammals, gradually lose the intestinal enzyme lactase after infancy and with it the ability to digest lactose, the principle sugar in milk. At some point in prehistory, a ...genetic mutation occurred and lactase activity persisted in a majority of the adult population of Northern and Central Europe. 2) Persistence of intestinal lactase, the uncommon trait worldwide, is inherited as a highly penetrant autosomal-dominant characteristic. Both types of progeny are almost equally common when one parent is a lactose maldigester and the other a lactose digester. 3) The incidence of lactose maldigestion is usually determined in adults by the administration in the fasting state of a 50-g dose of lactose in water, the equivalent of that in 1 L of milk. Measurement is made of either the subsequent rise in blood glucose or the appearance of additional hydrogen in the breath. It is also sometimes identified by measuring lactase activity directly in a biopsy sample from the jejunum. For children the test dose is reduced according to weight. Depending on the severity of the lactase deficiency and other factors, the test dose may result in abdominal distention, pain, and diarrhea. 4) The frequency of lactose maldigestion varies widely among populations but is high in nearly all but those of European origin. In North American adults lactose maldigestion is found in approximately 79% of Native Americans, 75% of blacks, 51% of Hispanics, and 21% of Caucasians. In Africa, Asia, and Latin America prevalence rates range from 15–100% depending on the population studied. 5) Whenever the lactose ingested exceeds the capacity of the intestinal lactase to split it into the simple sugars glucose and galactose, which are absorbed directly, it passes undigested to the large intestine. There it is fermented by the colonic flora, with short-chain fatty acids and hydrogen gas as major products. The gas produced can cause abdominal distention and pain and diarrhea may also result from the fermentation products. 6) Among individuals with incomplete lactose digestion, there is considerable variation in awareness of lactose intolerance and in the quantity of lactose that can be ingested without symptoms. A positive standard lactose test is not a reliable predictor of the ability of an individual to consume moderate amounts of milk and milk products without symptoms. In usual situations the quantity of lactose ingested at any one time is much less than in the lactose-tolerance test.
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